This invention relates to a device for automatically opening and closing the doors of automobiles and other vehicles.
As a known type of such devices there is one in which a push rod is connected to a part of a pillar of an automobile body offset from the pivot of the door hinge at one end and the door is made to open and close as the other end of this push rod is pushed and pulled by an appropriate drive means provided within the door.
According to this known device for automatically opening and closing automobile doors, the door has to be handled close to its hinges and, immediately before completely closing the door, the reaction force from the weather strips, lock resistance, air resistance, hinge resistance and so on act on the door, thereby making it necessary, for the purpose of securely closing the door, to forcibly close the door to utilize the inertia of the door or to increase the force effective in closing the door through the use of a powerful motor or a higher gear ratio.
However, when closing the door forcibly to let its inertia completely close the door, there is a great risk of deforming or damaging the door or the automobile body from impacts and of causing grave injuries to a passenger by catching part of his body inadvertently between the door and the automobile body as the door closes completely.
Using a powerful motor means not only greater weight and higher cost but also greater power consumption wnich will result in shortening the life of the automobile battery.
When the gear ratio is increased, the speed of opening and closing the door may become impractically slow.
Also, since a correspondingly great closure force is generated as the door closes completely, there is a risk that the door and the center pillar may be deformed.